Re: [eigen] AutoDiff: complex doesn't compile

[Christoph Hertzberg <chtz@xxxxxxxxxxxxxxxxxxxxxxxx>]

The template argument of AutoDiffScalar is supposed to hold the partial 
derivatives (which are always real). If you want complex AutoDiffs, all 
you can do is:

  typedef Eigen::AutoDiffScalar<Eigen::Vector2d> TpRFloat;
  typedef std::complex<TpRFloat> TpCFloat;

This does not take into account if functions are actually complex 
derivable, unfortunately.

Christoph



On 2016-09-11 16:56, Peter wrote:
> Dear All,
>
>
> in my Quest in using Eigen for own types, I realized, that
> Eigen::AutoDiff should posses the same difficulties.
>
> Sadly, I can't get even a simple case working.
>
> #include <complex>
>
> #include <Eigen/Dense>
> #include <unsupported/Eigen/AutoDiff>
>
> typedef Eigen::AutoDiffScalar<Eigen::Vector2cd> TpFloat;
> typedef Eigen::AutoDiffScalar<Eigen::Vector2d> TpRFloat;
>
> int main( const int argc, const char *argv[] )
> {
>     TpRFloat x(3.0) ;   // o.k.
>     TpFloat  z;   // not o.k.
>
>     return 0;
> }
>
> Eigen::AutoDiffScalar doesn't compile for complex types. Since the type
> definitions are within nested traits,
>     I couldn't spot a solution immediately.
>
> As note, the doc may clarify, that "the vector type used to
> store/represent the derivatives",
> means first-order derivatives, or gradients. I was first confused by
> assuming it would represent a Taylor
> expansion.
>
> Best regards,
> Peter
>
> __________________
>
> $ g++   -std=c++11 -DNDEBUG -O2  TestAutoDiff.C  -I $HOME/Eigen/eigen -o
> DiffPC 2>&1 | tee Err.txt | more
> In file included from
> /home/peter/Eigen/eigen/unsupported/Eigen/AutoDiff:32:0,
>                  from TestAutoDiff.C:5:
> /home/peter/Eigen/eigen/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h:
> In instantiation of 'struct
> Eigen::internal::auto_diff_special_op<Eigen::Matrix<std::complex<double>, 2,
> 1>, true>':
> /home/peter/Eigen/eigen/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h:67:7:
> required from 'class
> Eigen::AutoDiffScalar<Eigen::Matrix<std::complex<double>, 2, 1> >'
> TestAutoDiff.C:18:10:   required from here
> /home/peter/Eigen/eigen/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h:424:3:
> error: no type named 'Type' in 'class
> Eigen::CwiseUnaryOp<Eigen::internal::bind2nd_op<Eigen::internal::scalar_product_op<std::comp
>
> lex<double>, double> >, Eigen::Matrix<std::complex<double>, 2, 1> >'
>    operator*(const Real& other) const
>    ^
> /home/peter/Eigen/eigen/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h:432:3:
> error: no type named 'DerType' in 'class
> Eigen::CwiseUnaryOp<Eigen::internal::bind1st_op<Eigen::internal::scalar_product_op<double
>
> , std::complex<double> > >, Eigen::Matrix<std::complex<double>, 2, 1> >'
>    operator*(const Real& other, const AutoDiffScalar<_DerType>& a)
>    ^
> /home/peter/Eigen/eigen/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h:
> In instantiation of 'class
> Eigen::AutoDiffScalar<Eigen::Matrix<std::complex<double>, 2, 1> >':
> TestAutoDiff.C:18:10:   required from here
> /home/peter/Eigen/eigen/unsupported/Eigen/src/AutoDiff/AutoDiffScalar.h:81:25:
> error: no members matching
> 'Eigen::AutoDiffScalar<Eigen::Matrix<std::complex<double>, 2, 1> >::Base
> {aka Eigen::internal::auto_dif
> f_special_op<Eigen::Matrix<std::complex<double>, 2, 1>,
> true>}::operator*' in
> 'Eigen::AutoDiffScalar<Eigen::Matrix<std::complex<double>, 2, 1> >::Base
> {aka struct Eigen::internal::auto_diff_special_op<Eigen::M
> atrix<std::complex<double>, 2, 1>, true>}'
>      using Base::operator*;
>                          ^

--
 Dipl. Inf., Dipl. Math. Christoph Hertzberg

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